Magnetic random access memory structure and manufacturing method of the same

ABSTRACT

The present disclosure provides a magnetic random access memory structure, including an array region, and a logic region adjacent to the array region. The logic region includes a bottom electrode via, a magnetic tunneling junction layer over the bottom electrode via, a top electrode over the MTJ, a conformable oxide layer over the MTJ and the top electrode, and a silicon oxide layer over the conformable oxide layer. The conformable oxide layer and the silicon oxide layer extend from the array region to the logic region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of prior-filed provisionalapplication No. 62/593,005, filed Nov. 30, 2017.

BACKGROUND

Semiconductors are used in integrated circuits for electronicapplications, including radios, televisions, cell phones, and personalcomputing devices. One type of well-known semiconductor device is thesemiconductor storage device, such as dynamic random access memories(DRAMs), or flash memories, both of which use charges to storeinformation.

A more recent development in semiconductor memory devices involves spinelectronics, which combines semiconductor technology and magneticmaterials and devices. The spin polarization of electrons, rather thanthe charge of the electrons, is used to indicate the state of “1” or“0.” One such spin electronic device is a spin torque transfer (STT)magnetic tunneling junction (MTJ) device.

MTJ device includes free layer, tunnel layer, and pinned layer. Themagnetization direction of free layer can be reversed by applying acurrent through tunnel layer, which causes the injected polarizedelectrons within free layer to exert so-called spin torques on themagnetization of free layer. Pinned layer has a fixed magnetizationdirection. When current flows in the direction from free layer to pinnedlayer, electrons flow in a reverse direction, that is, from pinned layerto free layer. The electrons are polarized to the same magnetizationdirection of pinned layer after passing pinned layer; flowing throughtunnel layer; and then into and accumulating in free layer. Eventually,the magnetization of free layer is parallel to that of pinned layer, andMTJ device will be at a low resistance state. The electron injectioncaused by current is referred to as a major injection.

When current flowing from pinned layer to free layer is applied,electrons flow in the direction from free layer to pinned layer. Theelectrons having the same polarization as the magnetization direction ofpinned layer are able to flow through tunnel layer and into pinnedlayer. Conversely, electrons with polarization differing from themagnetization of pinned layer will be reflected (blocked) by pinnedlayer and will accumulate in free layer. Eventually, magnetization offree layer becomes anti-parallel to that of pinned layer, and MTJ devicewill be at a high resistance state. The respective electron injectioncaused by current is referred to as a minor injection.

The present disclosure provides an MRAM structure including MTJ deviceand manufacturing method of thereof, particularly to an MRAM structurewith reduced step height between memory array edge and logic region viasimplified manufacturing method to improve cycle time and reducemanufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a cross section of a magnetic random access memory structure,in accordance with some embodiments of the present disclosure.

FIG. 2A to FIG. 2L are cross sections of a magnetic random access memorystructure fabricated at various stages, in accordance with someembodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below.” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in therespective testing measurements. Also, as used herein, the term “about”generally means within 10%, 5%, 1%, or 0.5% of a given value or range.Alternatively, the term “about” means within an acceptable standarderror of the mean when considered by one of ordinary skill in the art.Other than in the operating/working examples, or unless otherwiseexpressly specified, all of the numerical ranges, amounts, values andpercentages such as those for quantities of materials, durations oftimes, temperatures, operating conditions, ratios of amounts, and thelikes thereof disclosed herein should be understood as modified in allinstances by the term “about.” Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the present disclosureand attached claims are approximations that can vary as desired. At thevery least, each numerical parameter should at least be construed inlight of the number of reported significant digits and by applyingordinary rounding techniques. Ranges can be expressed herein as from oneendpoint to another endpoint or between two endpoints. All rangesdisclosed herein are inclusive of the endpoints, unless specifiedotherwise.

Conventionally, MRAM structure includes bottom electrode via formation,MTJ formation, top electrode via formation, recap layer formation,photoresist etch back, and extreme low-k material (ELK) etch back, whichentail complex procedures and high cost. The conventional MRAM structurestill possess the problem of step height being too large, inducing ELKvoids between adjacent MTJs. The critical dimension of the conventionalMRAM structure is also difficult to scale down.

The present disclosure provides an MRAM structure and manufacturingmethod. The present disclosure help reducing step height of the MRAMstructure, and reducing ELK voids between adjacent MTJs. In addition,replacing the steps of top electrode via formation, recap layerformation, and ELK etch back may improve cycle time and reducemanufacturing cost.

Referring to FIG. 1, FIG. 1 is a cross sectional view of a magneticrandom access memory (MRAM) structure, in accordance with someembodiments of the present disclosure. The MRAM structure includes anarray region 11 and a logic region 12 adjacent to the array region 11.The array region 11 includes memory array, while the logic region 12includes at least one transistor. The array region 11 includes a siliconcarbide (SiC) layer 21, a silicon-rich oxide (SRO) layer 22 over the SiClayer 21, a bottom electrode via (BEVA) 23, a bottom electrode 24, amagnetic tunneling junction (MTJ) 25 over the BEVA 23, a top electrode26 over the MJT layer 25. In some embodiments, at least the bottomelectrode 24, the MTJ 25, and the top electrode 26 are collectivelycalled an MTJ structure in the present disclosure

Still referring to FIG. 1, the array region 11 further includes asidewall spacer 31 surrounding the MTJ structure, a protection layer 32over the sidewall spacer 31, a conformable oxide layer 33 over theprotection layer 32 and the sidewall spacer 31, a silicon oxide layer 34over the conformable oxide layer 33, a low-k dielectric layer 35 overthe silicon oxide layer 34, and an upper metal layer 13 as oppose to alower metal layer 11′. In some embodiments, the upper metal layer 13refers to an upper metal line and an upper metal via.

On the other hand, the logic region 12 includes a lower metal layer 12′,a silicon carbide (SiC) layer 21, a silicon-rich oxide (SRO) layer 22above the SiC layer 21, a conformable oxide layer 33 over the SRO layer22, a silicon oxide layer 34 over the conformable oxide layer 33, alow-k dielectric layer 35 over the silicon oxide layer 34, and an uppermetal layer 14. In some embodiments, the upper metal layer 14 refers toan upper metal line and an upper metal via. Like reference numberslabeled in the array region 11 and the logic region 12 representidentical components.

Referring to FIG. 1, in some embodiments, the conformable oxide layer 33and the silicon oxide layer 34 extend from the array region 11 to thelogic region 12. The conformable oxide layer 33 and the silicon oxidelayer 34 are formed simultaneously over the array region 11 and thelogic region 12. In some embodiments, area coverage of logic region 12and the memory region 11 are approximately 98% and 2% of total area ofthe wafer.

Still referring to FIG. 1, the sidewall spacer 31 surrounds the MTJ 25and the top electrode 26. In some embodiments, the sidewall spacer 31further covers a portion of the top surface of the top electrode 26. Insome embodiments, the protection layer 32 is over a top surface of thesidewall spacer 31, and further has a portion surrounding the lowersection of the sidewall spacer 31 contacting the SRO layer 22. In someembodiments, the conformable layer 33 is over the protection layer 32,while the silicon oxide layer 34 is over the protection layer 32, bothin the array region 11 and the logic region 12.

Referring to FIG. 2A through 2L, in some embodiments, a method formanufacturing an MRAM structure includes forming an MTJ structure in thearray region 11, forming the protection layer 32 over the MTJ structurein the array region 11 and in the logic region 12, removing theprotection layer 32 in the logic region 12, forming the conformableoxide layer 33 in the logic region 12, forming the low-k dielectriclayer (ELK) 35 over the conformable oxide layer 33 in the array region11 and the logic region 12, forming a dielectric stack 40 over the low-kdielectric layer 35 in the array region 11 and the logic region 12,forming an anti-reflective coating (ARC) 44 over the dielectric stack 40in array region 11 and the logic region 12, performing an ARC etch backand stopping the etch at the dielectric stack 40 in the array region 11and the logic region 12.

Referring to FIG. 2A, the MRAM structure includes an MTJ 25 at leastcomposed of ferromagnetic materials. A bottom electrode 24 and a topelectrode 26 are electrically coupled to the MTJ 25 for signal/biasconveyance. In some embodiments, the BEVA 23 is disposed over andelectrically coupled to a lower metal layer 11′ within array region 11.In some embodiments, the BEVA 23 possesses a conductive materialsfilling a trapezoidal recess surrounded by the silicon carbide (SiC)layer 21 and the silicon-rich oxide (SRO) layer 22 above SiC layer 21.Alternatively, the SRO can be replaced or combined with TetraethylOrthosilicate (TEOS). In some embodiments, the BEVA 23 may includeconductive materials such as metal. A planarization operation, such as achemical mechanical polishing (CMP) operation, may be applied to a topsurface of the BEVA 23. The bottom electrode layer is formed onto theBEVA 23. The bottom electrode layer may include TiN, TaN, W, Al, Ni, Co,Cu or the combination thereof. In some embodiments, a planarizationoperation, such as a CMP operation, may be applied to a top surface ofthe bottom electrode layer. In some embodiments, the material of thebottom electrode layer is different from that of the BEVA 23.

The MTJ layer is deposited in a form of multiple material stacks (notillustrated in FIG. 2A) over the bottom electrode layer. The MTJ layermay be formed by a variety of techniques, for example, high-densityionized metal plasma (IMP) deposition, high-density inductively coupledplasma (ICP) deposition, sputtering, physical vapor deposition (PVD),chemical vapor deposition (CVD), low-pressure chemical vapor deposition(LPCVD), plasma-enhanced chemical vapor deposition (PECVD), and thelike. The MTJ layer may include ferromagnetic layers, spacers, and acapping layer. The capping layer is formed on the ferromagnetic layer.Each of the ferromagnetic layers may include ferromagnetic material,which may be metal or metal alloy, for example, Fe, Co, Ni, CoFeB, FeB,CoFe, FePt, FePd, CoNi, TbFeCo, CrNi or the like. The spacer may includenon-ferromagnetic metal, for example, Ag, Au, Cu, Ta, W, Mn, Pt, Pd, V,Cr, Nb, Mo, Tc, Ru or the like. Another spacer may also includeinsulator, for example, Al₂O₃, MgO, TaO, RuO or the like. The cappinglayer may include non-ferromagnetic material, which may be a metal or aninsulator, for example, Ag, Au, Cu, Ta, W, Mn, Pt, Pd, V, Cr, Nb, Mo,Tc, Ru, Ir, Re, Os, Al₂O₃, MgO, TaO, RuO or the like. The capping layermay reduce write current of its associated MRAM cell. The ferromagneticlayer may function as a free layer whose magnetic polarity or magneticorientation can be changed during write operation of its associated MRAMcell. The ferromagnetic layers and the spacer may function as a fixed orpinned layer whose magnetic orientation may not be changed duringoperation of its associated MRAM cell. It is contemplated that the MTJlayer may include an antiferromagnetic layer in accordance with otherembodiments.

Following the formation of the MTJ layer, a top electrode layer isdeposited over the MTJ layer. The top electrode layer may be formed by avariety of techniques, for example, high-density ionized metal plasma(IMP) deposition, high-density inductively coupled plasma (ICP)deposition, sputtering, physical vapor deposition (PVD), chemical vapordeposition (CVD), low-pressure chemical vapor deposition (LPCVD),plasma-enhanced chemical vapor deposition (PECVD), and the like. In someembodiments, the top electrode layer and the bottom electrode layer aremade of a same material. In some embodiments, the material of the topelectrode layer is different from that of the BEVA 23 and the bottomelectrode layer.

A patterning operation is performed on the bottom electrode layer, theMTJ layer, and the top electrode layer to form bottom electrode 24, MTJ25, and top electrode 26. In some embodiments, the bottom electrode 24,the MTJ 25, and the top electrode 26 appear to have taper shape with awider section proximal to the bottom electrode 24 and a narrower sectionproximal to the top electrode 26.

As shown in FIG. 2A, a sidewall spacer 31 is a layer formed to surroundthe sidewall of the bottom electrode 24, the MTJ 25 and the topelectrode 26. In some embodiments, the sidewall spacer 31 may be asilicon nitride layer, which can be formed by a variety of techniques,for example, chemical vapor deposition (CVD), low-pressure chemicalvapor deposition (LPCVD), atmospheric pressure chemical vapor deposition(APCVD), and the like. In some embodiments, the sidewall spacer 31further covers a top surface of the top electrode 26. In someembodiments, the thickness 31 t of the sidewall spacer 31 over the topsurface of the top electrode 26 is approximately 40 angstrom. Thethickness 31 t of the sidewall spacer 31 will be subsequently discussedin FIG. 2L. Referring to FIG. 2B, the protection layer 32 is blanketdeposited over the SRO layer 22 of the array region 11 and the logicregion 12 and the top electrode 26 of the array region 11. In someembodiments, the protection layer 32 can be a silicon carbide (SiC)layer, which can be formed by a variety of techniques, for example,high-density ionized metal plasma (IMP) deposition, high-densityinductively coupled plasma (ICP) deposition, sputtering, physical vapordeposition (PVD), chemical vapor deposition (CVD), low-pressure chemicalvapor deposition (LPCVD), plasma-enhanced chemical vapor deposition(PECVD), and the like. In some embodiments, the thickness of theprotection layer 32 is approximately 400 angstrom. In some embodiments,the protection layer 32 further covers a top surface of the sidewallspacer 31 over the top electrode 26. Due to the poor coverage of formingthe protection layer 32 onto a sidewall of the sidewall spacer 31, thethickness of the protection layer 32 over the sidewall of the sidewallspacer 31 is negligible. In some embodiments, the thickness 32 t ofprotection layer 32 over the surface of the sidewall spacer 31 isapproximately 400 angstrom to 500 angstrom. The thickness 32 t of theprotection layer 32 will be subsequently discussed in FIG. 2L.

The protection layer 32 within the logic region 12 is subsequentlyremoved in order to reduce the thickness of the logic region 12 abovethe substrate, as shown in FIG. 2C. In some embodiments, a photoresist321 is patterned over the protection layer 32 to expose the logic region12. As shown in FIG. 2C, an etching operation, for example a dry etchoperation, can be applied herein to remove the protection layer 32within the logic region 12. In some embodiments, the dry etch in thepresent operation includes reactive ion etch (RIE) adoptingfluorine-containing gases. After removing the protection layer 32 in thelogic region 12, the photoresist 321 in the array region 11 can beremoved by applying plasma ashing or stripping. As shown in FIG. 2D, thethickness above the substrate within logic region 12 is reduced by athickness 32 t of protection layer 32. In some embodiments, thethickness 32 t of the protection layer 32 remained in the array region11 is approximately 400 angstrom.

One of the issues of conventional methods of producing MRAM structure isthe multiple voids in the low-k dielectric layer 35 due to the largeaspect ratio trench between adjacent MTJ structures, the low-kdielectric layer 35 may not be able to close the gaps between twoadjacent MTJ structures. Such voids may result in various problems insubsequent processing. Therefore, in some embodiments, the conformableoxide layer 33, as illustrated in FIG. 2E, is formed over the protectionlayer 32, extending from the array region 11 to the logic region 12.Application of the conformable oxide layer 33 of from about 300 Angstromto about 500 Angstrom reduces the aspect ratio of the trench betweenadjacent MTJ structures and thus alleviates the low-k dielectric layer35 voids problem.

In some embodiments, the conformable oxide layer 33 is a thin-filmdeposition layer. For example, the conformable oxide layer 33 can beformed by atomic layer deposition (ALD) or plasma enhanced atomic layerdeposition (PEALD). ALD is a layer-by-layer deposition process of thinfilms with conformal coating on 3D structures. The ALD operation may beperformed to improve the performance of filling narrow gaps or gaps withhigh aspect ratios. Precise control of thickness and film properties isfacilitated by adding precursors into the vacuum chamber during theprocess. Meanwhile PEALD is an advanced method of extending thecapabilities of ALD by applying radical gas species rather than water asoxidizer during the deposition process. In some embodiments, referringto FIG. 2F, current MTJ structure further includes forming another thinoxide layer 34, for example, Tetraethyl orthosilicate (TEOS) layer ofabout 150 Angstrom, above the conformable oxide layer 33. The thin oxidelayer also extends from the array region 11 to the logic region 12.

Referring to FIGS. 2G and 2H, the low-k dielectric layer 35 is formedabove the conformable oxide layer 33 and the thin oxide layer 34,extending from the array region 11 to the logic region 12. A dielectricstack 40 is further formed over the low-k dielectric layer 35, both inthe array region 11 and the logic region 12. In some embodiments, thedielectric stack 40 at least includes a first etch stop layer 41 and asecond etch stop layer 42 from bottom to top of the dielectric stack 40.In some embodiments, the first etch stop layer 41 include oxides, suchas Tetraethyl orthosilicate (TEOS). In some embodiments, the second etchstop layer 42 include oxynitride, such as Silicon Oxynitride (SiON).Optionally, a third layer 43 may include oxides similar to the firstetch stop layer 41. The function of the first etch stop layer 41 and thesecond etch stop layer 42 will be described subsequently in FIGS. 21, 2Jand 2K.

Referring to FIG. 21, the anti-reflective coating (ARC) 44 is formedover the dielectric stack in the array region 11 and logic region 12.Thence the ARC etch back operation is performed, as shown in FIG. 2J.Conventionally where the first etch stop layer 41 being absent from theMTJ structure, the ARC etch back operation adopts an end point detectionmode and overetches to the low-k dielectric 35 of the array region 11.Due to the fact that logic region 12 occupies 98% of the entiresubstrate area, end point detection start receiving sufficient end pointsignal when the dielectric layer 43 in the logic region is exposed.Nevertheless, the concurrent etch back operation in the array region 11has already advanced into the low-k dielectric 35, which has a greaterselectivity to etchant used in the etch back operation than that of thedielectric layer 43, causing an undesired recess in the array region 11.

Referring to FIG. 2J, in some embodiments of present disclosure, anadditional first etch stop layer 41 is disposed at the bottom of thedielectric stack 40, or at least partially overlapped in a lateral sensewith respect to the dielectric layer 43 in the logic region. In such ascase, when the end point detection start receiving sufficient end pointsignal while the dielectric layer 43 in the logic region being exposed,the concurrent etch back in the array region 11 would not advance to thelow-k dielectric 35 but rather being halted by the first etch stop layer41. Alternatively stated, the first etch stop layer 41 effectivelyprevent the ARC etch back operation from damaging the low-k dielectric35 in the array region 11.

Following FIG. 2J, a planarization operation is performed after the ARCetch back operation on the low-k dielectric 35, as shown in FIG. 2K. Incontract to conventional approach where a low-k dielectric etch back isperformed, present disclosure provides a planarization operation toremove the low-k dielectric 35 in the array region 11. In someembodiments, the planarization operation includes chemical mechanicalpolishing (CMP). A selectivity of the low-k dielectric layer 35 isgreater than a selectivity of the second etch stop layer 42 with respectto CMP in the planarization operation. Since the planarization operationis performed over the array region 11 and the logic region 12simultaneously, and that logic region 12 occupies 98% of the entiresubstrate area, the second etch stop layer 42 functions as an etch stoplayer to the low-k dielectric 35 of the array region 11 during theplanarization operation. In some embodiments, at the completance of theplanarization operation, a top surface of the low-k dielectric 35 in thearray region 11 is substantially coplanar to a top surface of the secondetch stop layer 42 in the logic region 12.

After the planarization operation is finished, the via trenches in thearray region 11 and the logic region 12 are formed simultaneously. Insome embodiments, the via trenches are formed by performing dry etchsuch as reactive-ion etching (RIE). RIE uses chemically reactive plasmato remove material deposited on substrates. The plasma is generatedunder low pressure by an electromagnetic field, as high-energy ions fromthe plasma etch the wafer surface.

As shown in FIG. 2L, via trench 13′ and 14′ are formed simultaneously inthe array region 11 and the logic region 12. In order to control viatrench 13′ and 14′ formation, the thickness and the materials of thelayers above the top electrode 26 in the array region 11 must becorrelated to the thickness and the materials of the layers above thelower metal line 12′ in the logic region 12. In some embodiments,referring to FIG. 2L, forming via trench 13′ of the upper metal layer 13within the array region 11 requires penetration through the low-kdielectric layer 35, the silicon oxide layer 34, the conformable oxidelayer 33, the protection layer 32, and the sidewall spacer 31 above thetop electrode 26. Similarly, forming via trench 14′ of the upper metallayer 14 in the logic region 12 requires penetration through the low-kdielectric layer 35, the silicon oxide layer 34, the conformable oxidelayer 33, the silicon rich oxide layer 22, and the silicon carbide layer21.

Based on the comparison of the removed compositions in array region 11and logic region 12, given the conformable oxide layer 33 and thesilicon oxide layer 34 both exist in the array region 11 and the logicregion 12, duration of via trench 14′ formation through the siliconcarbide layer 21 and the silicon rich oxide layer 22 in the logic region12 shall be substantially similar to duration of via trench 13′formation through the protection layer 32 and the sidewall spacer 31above the top electrode 26 in the array region 11. In some embodiments,the thickness of the silicon carbide layer 21 is approximately 300angstrom, and the thickness of the silicon rich oxide layer 22 isapproximately 200 angstrom. Accordingly, the protection layer 32 can bedesigned to exceed the thickness of the silicon carbide layer 21, forexample, approximate 400 angstrom, to compensate for the duration of viatrench 14′ formation through the thinner silicon carbide layer 21 andthe silicon rich oxide layer 22. In some embodiments, the thickness 31 tof the sidewall spacer 31 above the top electrode 26 is approximately 40angstrom to prevent the via trench 13′ formation operation from damagingintegrity of the top electrode 26.

After the trench is formed, conductive materials can be further filledinto the via trenches 13′ and 14′, as previously described, and intoline trenches (not shown). The metal vias may be formed by a variety oftechniques, e.g., electroplating, electroless plating, high-densityionized metal plasma (IMP) deposition, high-density inductively coupledplasma (ICP) deposition, sputtering, physical vapor deposition (PVD),chemical vapor deposition (CVD), low-pressure chemical vapor deposition(LPCVD), plasma-enhanced chemical vapor deposition (PECVD), and thelike. In some embodiments, the metal lines and metal vias are filledwith electrically conductive material, e.g. copper, gold or anothersuitable metal or alloy, to form a number of conductive vias. Metallines and metal vias in different metal layers form an interconnectstructure composed of substantially pure copper (for example, with aweight percentage of copper being greater than about 90 percent, orgreater than about 95 percent) or copper alloys, and may be formed usingthe single and/or dual damascene operations. Metal lines and metal viasmay be, or may not be, substantially free from aluminum.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother operations and structures for carrying out the same purposesand/or achieving the same advantages of the embodiments introducedherein. Those skilled in the art should also realize that suchequivalent constructions do not depart from the spirit and scope of thepresent disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

Some embodiments of the present disclosure provide a magnetic randomaccess memory (MRAM) structure, including an array region, and a logicregion adjacent to the array region. The logic region includes a bottomelectrode via, a magnetic tunneling junction over the bottom electrodevia, a top electrode over the MTJ, a conformable oxide layer over theMTJ and the top electrode, and a silicon oxide layer over theconformable oxide layer. The conformable oxide layer and the siliconoxide layer extend from the array region to the logic region.

Some embodiments of the present disclosure provide method formanufacturing a magnetic random access memory structure, the methodincludes forming a magnetic tunneling junction structure in an arrayregion, forming a protection layer over the MTJ structure in the arrayregion and in a logic region adjacent to the array region, removing theprotection layer in the logic region, forming a conformable oxide layerin the array region and the logic region, forming a low-k dielectriclayer over the conformable oxide layer in the array region and the logicregion, forming a dielectric stack over the low-k dielectric layer inthe array region and the logic region, forming an anti-reflectivecoating over the dielectric stack in the array region and the logicregion, and performing the an anti-reflective coating etch back andstopping the etch at the dielectric stack in the array region and thelogic region.

Some embodiments of the present disclosure provide method formanufacturing a magnetic random access memory structure, the methodincludes forming a magnetic tunneling junction structure in an arrayregion, forming a first dielectric layer over the MTJ structure in thearray region and a logic region adjacent to the array region wherein thefirst dielectric layer having a first selectivity, forming a first etchstop layer for an anti-reflective coating etch back operation whereinthe first etch stop layer having a second selectivity, and forming asecond etch stop layer for a planarization operation over the first etchstop layer wherein the second etch stop layer having a thirdselectivity. The first selectivity is greater than the secondselectivity in the anti-reflective coating etch back operation, and thefirst selectivity is greater than the third selectivity in theplanarization operation.

What is claimed is:
 1. A method for manufacturing a magnetic randomaccess memory (MRAM) structure, the method comprising: forming amagnetic tunneling junction (MTJ) structure in an array region; forminga protection layer over the MTJ structure in the array region and in alogic region adjacent to the array region; removing the protection layerin the logic region; forming a conformable oxide layer in the arrayregion and the logic region; forming a low-k dielectric layer over theconformable oxide layer in the array region and the logic region;forming a dielectric stack over the low-k dielectric layer in the arrayregion and the logic region; forming an anti-reflective coating (ARC)over the dielectric stack in the array region and the logic region; andperforming an ARC etch back and stopping the etch at the dielectricstack in the array region and the logic region.
 2. The method of claim1, wherein the ARC etch back stops at a first etch stop layer of thedielectric stack contacting the low-k dielectric layer.
 3. The method ofclaim 2, further comprising: performing a planarization operation overthe logic region and the array region thereby exposing the low-kdielectric layer in the array region; and stopping the planarizationoperation at the dielectric stack in the logic region.
 4. The method ofclaim 3, wherein the planarization operation stops at a second etch stoplayer above the first etch stop layer of the dielectric stack.
 5. Themethod of claim 3, further comprising simultaneously forming viatrenches in the array region and the logic region.
 6. The method ofclaim 5, wherein forming the via trenches in the array region comprisesremoving a portion of the conformable oxide layer and a portion of theprotection layer.
 7. The method of claim 5, wherein forming the viatrenches in the logic region comprises removing a portion of theconformable oxide layer.
 8. A method for manufacturing a magnetic randomaccess memory (MRAM) structure, the method comprising: forming amagnetic tunneling junction (MTJ) structure in an array region; forminga protection layer over the MTJ structure in the array region and in alogic region adjacent to the array region; removing the protection layerin the logic region; forming a low-k dielectric layer over the arrayregion and the logic region; forming a dielectric stack over the low-kdielectric layer in the array region and in a logic region adjacent tothe array region; and forming via trenches over the logic region andover the MTJ structure in the array region simultaneously.
 9. The methodof claim 8, wherein the via trench in the array region reaches a topsurface of a top electrode over the MTJ structure.
 10. The method ofclaim 8, wherein the via trench in the logic region reaches a topsurface of a metal line in the logic region.
 11. The method of claim 8,further comprising forming a conformable oxide layer in the array regionand the logic region prior to forming the low-k dielectric layer. 12.The method of claim 11, wherein forming the via trenches in the arrayregion comprises removing a portion of the conformable oxide layer and aportion of the protection layer.
 13. A method for manufacturing amagnetic random access memory (MRAM) structure, the method comprising:forming a magnetic tunneling junction (MTJ) structure in an arrayregion; forming a low-k dielectric layer over the MTJ structure in thearray region and a logic region adjacent to the array region; forming adielectric stack over the low-k dielectric layer in the array region andthe logic region, wherein forming the dielectric stack comprises:forming a first etch stop layer; and forming a second etch stop layerover the first etch stop layer, wherein the second etch stop layer isdifferent from the first etch stop layer; forming an anti-reflectivecoating (ARC) over the dielectric stack in the array region and thelogic region; and performing an ARC etch back and stopping the etch atthe first etch stop layer in the array region.
 14. The method of claim13, further comprising: forming a spacer over the MTJ structure; forminga protection layer over the spacer; and forming a conformable oxidelayer over the logic region and the array region.
 15. The method ofclaim 14, further comprising simultaneously forming via trenches in thearray region and the logic region after the planarization operation. 16.The method of claim 15, wherein forming the via trenches in the arrayregion comprises removing a portion of the conformable oxide layer, aportion of the protection layer, and a portion of the spacer.
 17. Themethod of claim 15, wherein forming via trenches in the logic regioncomprises removing a portion of the conformable oxide layer and aportion of the low-k dielectric layer.
 18. The method of claim 13,wherein: the low-k dielectric layer has a first selectivity; the firstetch stop layer has a second selectivity, wherein the first selectivityis greater than the second selectivity in the ARC etch back operation;and the second etch stop layer is for a planarization operation over thefirst etch stop layer, the second etch stop layer has a thirdselectivity, and the first selectivity is greater than the thirdselectivity in the planarization operation.
 19. The method of claim 13,wherein the first etch stop layer comprises oxide.
 20. The method ofclaim 13, wherein the second etch stop layer comprises oxynitrides.